The robot arms used in industry are classified as two categories including the se rial robot and the parallel robot. Compared with the serial robots, parallel robots have advantages in high precision, high stiffness, high load, high speed and low inertia. This work proposed and implemented a mechanism to perform spherical motion with merely extra modification of a Delta-based machine and the experimental results showed that this design is practical and stable for usage. According to the quantitative evaluation, the errors are within several millimeters.